widening steel wheels - newcastle region

[Guest001]

Backspace is just half the entire width (edge-to-edge, not bead-to-bead) of the wheel + offset. So let's just say your wheel is 220mm wide, and you want an offset of ET18. That means you want a backspacing of 110mm + 18mm = 128mm.

Wheel builders generally prefer using the term backspacing because it's easier to work with.

Do you mean half the rim or the tyre I guess talking about wheels it means the rim

In the link I posted it shows backspace as the distance between inside of face of hub to inner edge of rim

In that link you can compare two different rims and tyres and see exactly what the difference is.